MLB20 is worse than MLB19 by default. And I'm speaking directly to online gameplay, and not content, or showdowns, etc. etc.
The reason 20 is worse by default is because you would think that the game would improve and make advancements in their gameplay, as the year's go on, and not the other way around.
Also, patch updates do not necessarily mean that gameplay issues get fixed. A good example would be that update 1.05 patch notes indicated that, "In multiplayer games, slight increases made to pitch accuracy across all interfaces, including accuracy increases to perfect pitch inputs. Remember that other than user input, the pitcher's BB/9 and difficulty setting standards remain the biggest factors in overall accuracy. If you hit perfect meter more often you'll benefit from this update more than someone who doesn't." Obviously, whatever changes SDS made were not significant enough, because overall pitch accuracy is still a huge issue regardless of the pitcher's attributes.
The ONLY noticeable improvement made in 20 vs. 19, is that they finally improved the catcher's ability to block pitches in the dirt.